Marine propulsion assemblies with a pair of propellers driven by a single engine are known and have been in use for many years. For example, Krause U.S. Pat. No. 3,112,728 discloses a Twin Screw Power Motor Boat and Transmission Control. As disclosed, an internal combustion engine, a reduction gear and a drive shaft incorporate a bevel gear assembly in mesh with a pair of spaced bevel gears secured on the ends of a respective input shaft journaled and projected into a pair of transmissions.
A more recent U.S. Pat. No. 3,924,557 of Bloch discloses a propeller mechanism for boats, As disclosed, the device consists of two shafts attached to a gear mechanism which is enclosed in cowlings mounted opposite each other on the hull of a boat. Propellers are mounted on the shafts, in addition, supports are provided attached to the splash board which also support two rudders mounted behind the propellers. The gear mechanism is connected to a motor controller located inside of the boat.
Finally a Multi-Propeller Drive System is disclosed in Belenger, U.S. Pat. No. 5,413,512. As disclosed the system includes a single input shaft for connection to an engine, a differential gear assembly for directing the driving force from the input shaft between a pair of output shafts and a pair of laterally spaced propellers driven by the output shafts of the differential gear assembly. The differential gear assembly operates in a manner wherein one output shaft if required is permitted to revolve at a different speed than the other output shaft. A pair of brake mechanisms acting on the output shafts of the differential gear assembly enables an operator to control the rotational speed of the respective propellers without modifying the engine speed or transmission setting
Notwithstanding the above, it is presently believed that there is a need and a potential commercial market for an improved marine propulsion assembly in accordance with a preferred embodiment of the present invention. There should be a demand for such assemblies because they power twin propellers with a single engine to reduce the cost for a second engine, reduce the load or weight on the boat and possibly conserve fuel. Also, it is believed that the unique design of the propellers increase thrust and enhance the triple mechanism of the marine propulsion assembly.